Hand operated tools for cutting tubing, light pipe, and other hollow cylindrical materials are well known. Such devices generally include at least one cutting blade or wheel disposed opposite at least two rollers, thus providing triangulation and positive location around the circumference of the material being cut. The cutting device is rotated about the circumference of the material being cut, in order to move the cutting blade completely around the material.
One feature universal to all such cutting devices is a means to advance the cutting blade into the material being cut as the operation is performed, due to the ever increasing depth of the cut as the operation progresses. As can be seen, if the cutting blade is not advanced, an initial shallow cut would be made about the circumference of the material and no further cutting action would take place. The general method for advancing the cutting blade in such implements is by means of a threaded screw advance of the rotary cutting blade. The positive advancement thereby provided is extremely effective, but generally requires manual advancement of the cutting blade by means of the screw adjustment every one or two turns of the cutter around the material. This is obviously a tedious procedure if the material being cut has a relatively thick wall. Moreover, great care must be used in advancing the cutting blade, as the blade edge may be dulled or damaged, or the axis of the rotary cutting blade may be displaced, if the screw advance is tightened too much. On the other hand, too little force on the cutting blade advance results in a relatively slow and inefficient cutting operation.
Additional features are desirable in such cutters to further enhance the cutting operation, such as the incorporation of means allowing some circumferential movement of the cutting blade to better balance the forces on the blade and rollers. Due to the geometry of at least one embodiment of the present invention, such circumferential movement of the cutting blade may be desirable in order to properly triangulate the cutting blade and support rollers. Such a feature should also provide further fine adjustment in the spring force biasing the cutting blade or wheel toward the rollers in order to optimize the cutting rate and pressures.
The need arises fur a cutting tool for tubing or the like, which tool is capable of automatically providing constant pressure to the material being cut by the cutting blade or wheel, thereby obviating any requirement for manual adjustment of the tool during the cutting operation. Further, means are needed to allow the cutting blade or wheel to "float" to a certain extent, thereby allowing the cutting blade to adjust to the optimum geometry depending upon the diameter of the material being cut, and further to allow fine adjustment of cutting pressure.